The present invention relates to a speed control structure for a working vehicle, particularly a front mower type garden tractor, having a stepless change speed apparatus which provides backward drive as well as forward drive across a neutral position.
There are working vehicles such as front mower type garden tractors that have a hydrostatic transmission which is one example of change speed apparatus as noted above. An example of change speed structure for operating the hydrostatic transmission is disclosed in Japanese Patent Publication Kokai No. 60-146729. This construction comprises a change speed pedal including a first pad for forward drive and a second pad for backward drive at longitudinally opposite ends thereof. The change speed pedal is mechanically connected to the hydrostatic transmission through rods and the like.
With the disclosed construction, a backward and forward changeover as well as acceleration and deceleration are effected by a down-toe motion applied to the first pad for forward drive and a down-heel motion applied to the second pad for backward drive after moving the foot rearwardly. It is difficult to repeat the backward and forward changeover frequently and promptly because the foot must be moved over an extensive range. Furthermore, it is difficult to effect delicate speed controls for the backward drive by depressing the second pad with the heel.
To overcome such disadvantages, a different construction has been used in which a forward change speed pedal and a backward change speed pedal are arranged side by side for depression by the toe end of a foot. In this instance, the two pedals are operatively connected to the hydrostatic transmission, respectively, which requires two separate interlocking lines for forward drive and backward drive, resulting in a complicated construction.